A pedometer is a device, usually portable and electronic or electromechanical, that counts each step a person takes by detecting the motion of the person's hands or hips. Because the distance of each person's step varies, an informal calibration, performed by the user, is required if presentation of the distance covered in a unit of length (such as in kilometers or miles) is desired, though there are now pedometers that use electronics and software to automatically determine how a person's step varies. Distance traveled (by walking or any other means) can be measured directly by a GPS watch.

Used originally by sports and physical fitness enthusiasts, pedometers are now becoming popular as an everyday exercise counter and motivator. Often worn on the belt and kept on all day, it can record how many steps the wearer has walked that day, and thus the kilometers or miles (distance = number of steps × step length). Some pedometers will also erroneously record movements other than walking, such as bending to tie one's shoes, or road bumps incurred while riding a vehicle, though the most advanced devices record fewer of these 'false steps'. Step counters can give encouragement to compete with oneself in getting fit and losing weight. A total of 10,000 steps per day, equivalent to 8 kilometres (5.0 mi), is recommended by some to be the benchmark for an active lifestyle, although this point is debated among experts. Thirty minutes of moderate walking are equivalent to 3,000-4,000 steps as determined by a pedometer.[1] Step counters are being integrated into an increasing number of portable consumer electronic devices such as music players, smartphones, and mobile phones.

Pedometers can be a motivation tool for people wanting to increase their physical activity. Various websites exist to allow people to track their progress; however, many will also find entering their daily step count and a heart-beat count onto a calendar to be motivational as well. Pedometers have been shown in clinical studies to increase physical activity, and reduce blood pressure levels and Body Mass Index. A study published in the Journal of The American Medical Association Nov. 2007[2] concluded, “The results suggest that the use of a pedometer is associated with significant increases in physical activity and significant decreases in body mass index and blood pressure.”

A daily target of 10,000 steps was first proposed.[3] The target has been recommended by the US Surgeon General and by the UK Department of Health.[4][5] The main criticisms of setting a universal target are that it is not achievable for older persons with mobility problems or people with chronic diseases, but on the other hand, the target is probably too low for children.[4]

One criticism of the pedometer is that it does not record intensity, but this can be done by making step goals time limited (for example, 1000 steps in 10 minutes counts as moderate exercise).[6]

Leonardo da Vinci envisioned a mechanical pedometer as a device with military applications.[7][8] In 1780 Abraham-Louis Perrelet of Switzerland created the first pedometer, measuring the steps and distance while walking; it was based on a 1770 mechanism of his to power a self-winding watch.[9] A mechanical pedometer obtained from France was introduced in the US by Thomas Jefferson.[10] It is not known if he modified the design; although this pedometer is widely attributed to Jefferson,[11][12] proof is difficult to obtain as he did not apply for patents on any of his inventions.[13]

In 1965 a pedometer called a manpo-kei (meaning "10,000 steps meter" Japanese: 万歩計) was marketed in Japan by Y. Hatano.[14] Y. Hatano promoted "manpo-kei pedometers" from 1985, after his research was accepted as proving that 10,000 Steps A Day was the proper balance of caloric intake and activity-based caloric expenditure to maintain a healthy body. Jiro Kato, who founded Yamasa Tokei Keiki Co., Ltd. in Tokyo, manufactured pedometers recognized to be accurate, and named them "manpo-meter" (later "manpo-kei", registered as a trademark of the company), claimed to be the world's first device to measure number of steps of walking.[15]

The technology for a pedometer includes a mechanical sensor and software to count steps. Early forms used a mechanical switch to detect steps together with a simple counter. If one shakes these devices, one hears a lead ball sliding back and forth, or a pendulum striking stops as it swings. Today advanced step counters rely on MEMS inertial sensors and sophisticated software to detect steps. These MEMS sensors have either 1-, 2- or 3-axis detection of acceleration. The use of MEMS inertial sensors permits more accurate detection of steps and fewer false positives. The software technology used to interpret the output of the inertial sensor and "make sense of accurate steps" varies widely. The problem is compounded by the fact that in modern day-to-day life, such step-counters are expected to count accurately on locations where users frequently carry their devices (attached to the belt, shirt/pants pocket, hand bag, backpack).

The accuracy of step counters varies widely between devices. Typically, step counters are reasonably accurate at a walking pace on a flat surface if the device is placed in its optimal position (usually vertically on the belt clip). Although traditional step counters get affected dramatically when placed at different angles and locations, recent advances have made them more robust to those non-ideal placements. Still, most step counters falsely count steps when a user is driving a car or makes other habitual motions that the device encounters throughout the day. This error accumulates for users with moderate commutes to work.[16] Accuracy also depends on the step-length the user enters.

Apple and Nike, Inc. offer the Nike+iPod Sports Kit, which uses a motion sensor that fits into a Nike shoe or in a pocket worn on the laces of other brands of shoes. The sensor communicates with an iPhone (3GS or higher), iPod touch (2nd generation or higher), iPod nano (4th generation or higher), or dedicated adapter to transmit workout information such as elapsed time, distance traveled, and calories burned.

The iPhone 5s was the first iPhone to contain an Apple Motion Coprocessor which was denoted the M7 chip paired with the first 64-bitARM-based Apple processor, the Apple A7 SoC (System on a Chip). The addition of the separate always on coprocessor allows the main CPU to snooze while it tracks the motion of the phone, through the use of an inertial measurement unit (IMU) consisting of an accelerometer, MEMS gyroscope and digital compass. This means that it will know when you're jogging or when you're in the car, and can take that information and store it without needing to drain the battery by having the main CPU run. It can retrofit the data to apps that you download at a later date, meaning any M7-enabled app that uses the new CoreMotion API will be able to give you information on recent training.

The iPhone 6 and 6 Plus contains the next generation of the Apple Motion Coprocessors with the M8 motion coprocessor, this chip was paired with the vastly improved Apple A8 SoC processor and gained the added sensor input of a Bosch Sensortech Barometer allowing the M8 to sense changes in elevation by the change in barometric pressure.

The iPhone 6s and 6s Plus improved the Apple Motion Coprocessors by adding integrating it into the die of the new Apple A9 SoC processor. This saves space allowing for the reduction of the logic board size as well as reduced power usage within the phone. This chip is also at the heart of the iPhone SE. A variant of the Apple A9, the Apple A9X also incorporates the M9 processor on-die and drives the Apple iPad Pro.

The Fitbit is an always-on electronic pedometer, that in addition to counting steps also displays distance traveled, altitude climbed (via a number of flights of steps count), calories burned, current intensity, and time of day. Worn in an armband at night, it also purports to measure the length and quality of a user's sleep. Inbuilt is a daily target, of 10,000 steps and 10 flights of stairs. Connected by USB with a computer, the user's data is automatically uploaded and displayed via a web-based profile page, that keeps track of historical data, to which can be added food consumption data. Based on activity users are awarded badges for daily step and climbing targets, as well as 'lifetime' awards for same. In the US and UK users can also download an iOS or Android app for recording and display of data.[20] Most Fitbit devices estimate distance traveled based on steps counted, the intensity of the steps and the user's profile data (specifically gender and height). Individuals can improve the accuracy of their stride length settings by measuring and calibrating their average stride length.[21] Some higher-end Fitbit models include additional features such as heart rate monitoring and GPS tracking.

Since most smartphones, iPod Touches and some MP3 players are enhanced with an integrated accelerometer it is possible to introduce pedometer functionality to these devices. This option was successfully realized by a number of smartphone application developers, enabling any fitness savvy smartphone owner to track the number of steps taken as well as distance traveled and calories used.

This is the first integrated phone with an always-on pedometer which counts steps like a traditional pedometer. The sensor is made by ADI. This handset was introduced in Japan in 2004 and has sold over 3 million units.[22]

The Nokia 5500 Sports Phone uses an embedded 3 axis MEMS inertial sensor to detect the steps a user takes. The pedometer application tracks steps taken, time elapsed and distance traveled. However the application cannot run continuously as it drains the phone's battery and is therefore of limited use.

Nokia Sports Tracker features pedometer for Nokia Symbian phones with an Accelerometer. Accelerometers are included in phones to save correct orientation on photos and to improve the GPS positioning feature.

Nokia Step Counter is a free application available at Nokia Beta Labs which works on a wide range of N-Series Nokia phones. The pedometer application tracks steps taken, time elapsed and distance traveled. This application can be left running all day as it is not a huge drain on the battery.

The Sony Ericsson W710 and W580 walkman phones use embedded 2 axis MEMS inertial sensors to detect the steps a user takes. The W710 is a clamshell phone and displays the user's steps on the external display. The W710 must be closed in order for it to count steps. When the step counter is activated, it counts detected steps during the day, and at midnight it stores the counter in a day-by-day history and resets it to zero.

On September 12, 2009, Nintendo released Pokémon HeartGold and SoulSilver in Japan. Each game comes bundled with a device called a Pokéwalker, which functions as a pedometer and allows players to transfer one Pokémon from their game to the Pokéwalker via infrared signals. Unlike the Personal Trainer: Walking pedometers, the Pokéwalker features a small LCD screen and multiple buttons. Walking with the Pokéwalker earns experience points for the Pokémon.[23]

The Nintendo 3DS, released March 27, 2011, features an internal pedometer that counts and records daily step counts while in sleep mode. Every hundred steps earns a Play Coin, which can be spent on a variety of extras and bonuses.[24] This pedometer is easily fooled, however, and 'steps' can be created by simply lifting the device up and down in the hand with a motion similar to walking.[25]

Tractivity is a group of health related services which include a sensor that is worn on a shoe. The Tractivity sensor logs the distance a person walks or runs, the calories burned and the time the person was active. Their data shows up on the individuals private web page. Tractivity's online web application provides a graphical experience and motivational resource to encourage people to lead healthier lifestyles, something that pedometers do not traditionally include. Tractivity is able to account for the variation in a walkers or runner’s stride length that occur as pace changes. The sensors wirelessly transfer activity data to a secure server for viewing on an individuals computer.[27]

A device already supporting this sensor is the Nexus 5. Another smartphone is the Samsung Galaxy S5, which features a built-in pedometer that uses the S Health software to display your daily step counts.